X-ray film



United States Patent X-RAY FILM Jean E. Jones and Rudolph E. Damschroder, Rochester,

N. Y., assignors to Eastman Kodak Company, Rochester, Y., a corporation of New Jersey No Drawing. Application June 4, 1952, Serial No. 291,801

4 Claims. (Cl. 95-8) This invention relates to novel photographic elements which are useful for obtaining X-ray photographs or radiograms, and to a method for processing such elements.

The desensitization of certain film coatings by strains produced in large sheets by improper handling so as to produce kink marking is well-known. The problem is particularly troublesome in high-speed, negative, silverbromiodide emulsions, such as those used in X-ray diagnosis. Since such emulsions are considerably thicker than those customarily employed in photography, the tendency toward kink marking is quite enhanced. Moreover, the tendency to show such desensitization becomes much worse in many instances after the coated film has been aged.

We have now found that the addition of certain antikinking agents can be used to effectively reduce the tendency toward kink desensitization in certain film coatings. Typical anti-kinking agents comprise alkylbenzothiazolium salts, rhodanine, 3-alkylrhodanines, alkylene bis-(3,3'-rhodanines), 3-arylrhodanines, 2-mercaptobenzothiazoles, N,N-ethylenethiourea (2-mercapto-A -imidazoline), 2-(A -imidazolinyl)disulfide, urazole, bis-(4- morpholinylthiocarbonyl)disulfide, diarylsulfides, diaryldisulfides, bis-(guanyl)disulfide, bis-(arylmethyl)disulfides, alkyl S-(benzoyl) xanthates, dialkyl phthalates, amides of carboxylic acids containing at least 9 carbon atoms in the acid radical, quinitol Z-ethylhexoate, and polymerized ethylenically unsaturated compounds which are compatible with gelatin. The reasons for the unique behavior of the above anti-kinking agents are not apparent in every instance and We do not wish to limit our invention to any particular theory or hypothesis, since the reasons for this behavior have not been fully investigated.

It is, therefore, an object of our invention to provide novel photographic elements adopted for use in X-ray photography. A further object is to provide a means of preparing such elements. Still another object is to provide a means of processing such photographic elements. Other objects will become apparent from a consideration of the following description and examples.

Photographic elements used in X-ray photography generally comprise a base support having superimposed on each side of the support a photosensitive layer. Such elements generally have a protective layer coated over each emulsion layer, the protective layers containing a nondiffusing, light-absorbing material (see Murray U. S. Patent 2,379,373, issued June 26, 1945). The photosensitive layers customarily employed in such elements have a thickness of from about 0.4 to 1.2 mils, and are generally high speed, negative silver bromiodide emulwherein Z1 represents the non-metallic atoms necessary wherein R represents an alkyl group of at least nine carbon atoms, such as n-nonyl, n-decyl, n-dodecyl (lauryl), n-hexadecyl (cetyl), etc., X represents an acid radical such as chloride, bromide, iodide, benzenesulfonate, p-toluenesulfonate, perchlorate, etc., and Z represents the non-metallic atoms necessary to complete a heterocyclic nucleus of the benzothiazole series. Typical alkylbenzothiazolium salts include:

1. 3-n-laurylbenzothiazolium iodide. 2. 3-n-cetylbenzothiazolium iodide. 3. 3-n-lauryl-5-phenylbenzothiazolium iodide.

The rhodanine, S-alkylrhodanines, and 3-arylrhodanines which can be used in practicing our invention can advantageously be represented by the following general formula:

II. O=C'-N Rl H247 J=S s wherein R1 represents a hydrogen atom, an alkyl group,

such as methyl, ethyl, B-hydroxyethyl, n-heptyl, carbethoxymethyl, n-dodecyl (lauryl), carboxymethyl, etc., or an aryl group, such as phenyl, p-dimethylaminophenyl, etc. Typical are:

. Rhodanine.

. 3-carboxymethylrhodanine.

. 3-n-laurylrhodanine.

. 3-ethylrhodanine.

. 3-phenylrhodanine.

. 3-p-dimethylaminophenylrhodanine.

The N,N-alkylenerhodanines which can be used in practicing our invention can advantageously be represented by the following general formula:

1L o=o N-(oHz) .N- o=o H; :S S: 43H:

S wherein n represents a positive integer of from 2 to 10. Typical bis-rhodanines include: 10. Ethylene bis-(3,3-rhodanine) 11. Decamethylene bis-(3,3'-rhodanine).

The Z-mercaptobenzothiazoles which can be used in practicing our invention can advantageously be represented by the following general formula:

to complete a heterocyclic nucleus of the benzothiazole series. Typical Z-mercaptobenzothiazoles include:

12. 2-mercaptobenzothiazole. 13. 5-chloro-2-mercaptobenzothiazole. 14. 5- methyl-2-mercaptobenzothiazole.

The N,N-ethylenethiourea (2-mercapto-A -imidazoline)"which"can be used in practicing our invention can be represented by the following formula:

15. N',N'-'ethylen'ethiourea.

The-2-(A imidazolinyl)disulfide which can be used in practicing our invention can be represented by 'the following formula:

HzCN

HzC-N N-CHz H H 16."2'-A -imidazolinyl)disulfide (as hydrochloride).

'The urazole' which can be used in practicing our invention can berepresented by the following formula:

ll HN-C The bis-('4-morpholinylthiocarbonyl)disulfide which can be used in our invention can be represented by the following formula:

18. Bis-I4-morpholinylthiocarbonyl)disulfide.

The 'diaryl sulfides which can be used in practicing our invention can advantageously be represented by the following general formula:

wherein R2 and R3 each represents an aryl group; such' as phenyl, p-aminophenyl, etc. Typical are:

19. Diphenylsulfide. 20. p,p'-Diaminodiphenylsulfide.

The diaryldisulfides which can be used in. practicing our invention can advantageously be represented by the following general formula:

whereinRtandRseachrepresents an aryl'group, such as phenyl, oand p-aminophenyl, o-' and p-dirnethylaminophenyl, etc. Typical are:

21. Diphenyldisulfide.

22. o,o'-Diaminodiphenyldisulfide.

23.- p,p'-Diarninodiphenyldisulfide.

24. p,p-Di-(dimethylamino)diphenyldisulfide.

The bis-(ary1n1ethyl)disulfides which-"'can be'us'ed in practicing our invention can advantageously be represented by the following general formula:

wherein R6 and R7 each represents an aryl group, such as phenyl, 4-hydroxy-3-methoxyphenyl, etc. Typical are 26. Dibenzyldisulfide. 27. Di-(4-hydroxy-B-methoxybenzyl)disulfide.

The alkyl S-(benzoyl)xanthates which can be used in practicing our invention can advantageously be represented by the following general formula:

wherein Ra represents an aryl group, such as phenyl,o-, m-, and p-tolyl, etc. and R9 represents an alkyl group, such as methyl, ethyl, n-propyl, etc. Typical are:

28. Ethyl S-benzoylxanthate. 29. Ethyl S-(p-chlorobenzoyl)xanthate.

The dialkyl phthalates which can be used in practicing our invention can advantageously be represented by the following general formula:

COORio wherein R10 represents an alkyl group, such as methyl, ethyl, n-propyl, n-butyl, etc. Typical are:

30. Dimethylphthalate. 31. Diethylphthalate. 32. Di-n-butyl phthalate.

The amides of carboxylic acids which can be used'in practicing our invention can advantageously be represented by the following general formula:

wherein R11 represents an alkyl group of at least 8 carbon atoms, such as n-octyl, n-nonyl, n-undecyl, etc., R12 and R13 each represents a hydrogen atom or an alkyl group, such as methyl, ethyl, etc. Typical are;

The'quinitol 2-ethylhexoate'which can be used in pracn-Pelargonamide.

N-methyl n-pelargonamide. n-Lauramide. N,N-diethyl-n-lauramide. N,N-dimethylcapramide.

ticing our invention can advantageously be represented by the following formula:

' 38. Quinitol 2-ethylhexoate.

. The polymerized, ethylenically-unsaturated compounds which are compatible with gelatin comprise a large'number of synthetic resins grouped together as vinyl and butadiene resins. Typical, for example, are:' copolymers of acrylonitrile with acrylic esters, such as:

39. Acrylonitrile-ethyl acrylate copolymer. (Rhopleic) Copolymersof b'utadiene, such as:

40. Butadiene-styrene copolymer-(e.l g. 1:1), 41. Butadiene-acrylonitrile"copolymer,

Copolymers of styrene with acrylic esters, such as:

42. Styrene-ethyl acrylate copolymer. 43. Styrene-butyl acrylate ccpolymer (e. g. 1:1),

Polymers of vinyl acetate, such as:

44. Polyvinyl acetate.

Polyacrylamides; polyvinyl alcohols; etc.

The optimum concentration of anti-kinking agent can be determined by making the ordinary observations customarily applied in emulsion making. The amount, of course, will vary from agent to agent and emulsion to emulsion. The anti-kinking agent can be incorporated in the emulsions by any of the means usually employed in the art. For example, a stock solution can be prepared by dissolving the agent in a suitable solvent, such as methanol, acetone, pyridine, etc. Then into one liter of a fiowable photographic gelatino-silver-halide emulsion an amount of the stock solution (diluted somewhat, if desired) is incorporated. The emulsion containing the anti-kinking agent is then coated on a suitable support, such as a cellulose derivative (e. g. acetate, nitrate, acetate butyrate, etc.), synthetic resin, such as polyvinyl acetate, polyvinyl acetal, etc., and allowed to dry, details of these processes being well-known to those skilled in the art of photography. Advantageously, the emulsion is applied to both sides of the support and has a thickness not less than about 0.4 mil. For testing the efiiciency of a particular polymethine dye, a single layer emulsion is sufiicient.

In most cases the eflfect is readily visible in the fresh film coating, but in many cases the best effect is obtained only after the film has been aged artificially (prior to kinking) at 120 F. at 45 per cent relative humidity for 3 days or longer. In some instances there is even some apparent improvement after aging, the reasons for which have not been fully investigated.

The anti-kink marking effect is best observed by means of a triangle and sensitometric bend test. The triangle test involves compression of the film coating between two plates, one of which has a raised triangle and the other of which has a triangle of about three times the area of the first cut in it. The raised triangle is an isosceles triangle, the longer sides being about in length, the shorter side being about A in length. The ofiset of the raised triangle is about and the proportions of the depressed triangle are the same as those of the raised triangle. For testing purposes, a 3 kg. weight is applied to the top of the raised triangle. The sensitometric bend test involves bending a strip of the film through an angle of about 90 (the radius of curvature being about in most instances), the radius of curvature being great enough so that the film in strip form, is not creased. The film after kinking is then given either a uniform flash or is exposed in an Ib sensitometer, and developed, fixed, washed and dried in the usual manner. The spectral distribution of the light source is adjusted by means of a filter to be almost identical with that emitted by a standard fluorescent screen, such as is customarily employed in X-ray photography. Of course, when using the sensitometric bend test, the bending is done longitudinally, so that each step in the exposure by the simulated X-ray screen is crossed by the line of kinking. The results of the triangle and sensitometric bend test parallel each other generally. In some instances the film was aged at 120 F. at 45 percent relative humidity for 3 days before kinking, and the results of these tests are given in the tables below in the columns headed AD after 3 days/ 120 F./45% R. H.

The efiectiveness of a particular anti-kinking agent can be observed by visual comparison between the density of the unatfected and kinked portions of the film, or by making actual density measurements. When using the sensitometric bend test, numerical data were obtained by a microdensitometer trace of the sensitometric step whose gross density was closest to 0.5. The difi'erence in density between the normal density of the step and the minimum density in the kinked portion was measured. The difference is designated AD in the tables which follow. The effects of the triangle bend test were observed visually.

In the above manner, various anti-kinking agents were dissolved in a suitable solvent and the solutions added to gelatino-silver-bromiodide emulsions, and after a short after-ripening, the emulsions were coated on a cellulose acetate support and dried.

In the case of compounds 30-38 incorporation was effected by dispersing the anti-kinking compounds in gelatin dispersions rather than by means of solvents as in the case of the other compounds. The anti-kink marking effect of the various anti-kinking agents was tested by either of the methods described above. The amount of agent per mol. of silver halide and results are given in the tables below. The AD given in some of the tables is a microdensitometer measurement of the difference between normal density and minimum density in the kinked portion where gross normal density is nearest 0.5. The exposures in each instance were made with light filtered in such a manner as to give a spectrum almost identical to that emitted by an X-ray screen. The results are given in the tables which follow.

The results given in the table below were recorded from visual observations, and not from densitometer measurements. The efiects were rated on a basis of 0 for no kinking, 1 for very slight kinking, 2 for some kinking, 3 for some improvement, and 4 for no improvement.

TABLE I TRIANGLE BEND KIN K TESTING Anti-Kinking Agent Amount, Residual g./mol. Kink 1 TABLE II TRIANGLE BEND KINK TESTING Anti-Kinking Agent Amount, Residual Kink 1 OMOb-OWHNOJHWHMO QOHOHODNNMMHMHHHMHN) 1 After three days at F., 45% R. H.

7 TABLE I11 SENSITOMETRIO BEND KINK TESTING Amount, AD after 3 Ant1-Kinklng Agent gJmol. AD days/120 F./

1 Contained dibutyl phthalate as a plasticizer.

In addition to being provided with a light-sensitive layer on either side of the support, the novel X-ray sensitive photographic elements of our invention can have subbing layers, such as antihalation layers, intermediate between the support and the light-sensitive emulsions, and overcoating layers, which permit handling of the elements in daylight without fogging, such for example, as is described in U. S. Patent 2,379,373 mentioned above. For example, a gelatin overcoat containing dispersed car-- bon can be used. Alternatively, the protective lightdispersing layers can consist of a dispersion of finely divided carbon in a mixture of colloids, such as gelatin and casein, or gelatin and a synthetic resin, e. g. a polyvinyl acetal, etc. The same type of anti-kinking agent need not be incorporated in each emulsion layer. Moreover, a mixture of anti-kinking agents can be incorporated in a single emulsion, such for example as is illustrated in Table III above (agent 44 Anti-kinking agent 1 used above was prepared as follows:

Example A.-3-n-laurylbenz0thiazolium iodide A mixture of 4.5 g. (1 mol.) of benzothiazole and 9.9 g. (1 mol.) of lauryl iodide was heated in an oil bath at 113-118" C. for 65 hours. The viscous prodnot was washed with absolute ether. The remaining residue was stirred with hot ethyl acetate. After chilling and stirring, the crystalline. product was collected on a filter and washed with ethyl acetate. The yield of quaternary salt was 86%v crude and 74% after two recrystallizations from ethyl acetate. The almost colorless crystals had melting point 9192 C.

Anti-kinking agent 9 used above was prepared as follows:

A solution of 34 g. (1 mol.) of carboxymethyltrithiocarbonic acid (HOOCCHzSCSSCHzCOOH), 35 g. (1 mol.) of p-amino-dimethylaniline sulfate and 16 g. (1 mol.) of sodium carbonate in 600 ml. of water was heated, under reflux, at the temperature of the steam bath for seven hours. After cooling, the solid was collected on a filter and washed with water. The yield of pale yellow crystals was 87%. A one-gram sample was recrystallized from methyl alcohol. The pale yellow crystals had melting point 211-213" C.

Anti-kinking agent 16 used above was prepared according to the method of Werner, I. C. 5., vol. 101, pg. 2171.

Anti-knking agent 18 has been previously described by Braun, Ben, vol. 35 (1902), pg. 817. Anti-kinking agent 29 has been previously described by Bullmer and Mann, I. C. S. (1945), pg. 679. Anti-kinking agent 27 has been previously described by Manchot and Zahn, Ann, vol. 345 (1906), pg. 320.

Anti-kinking agent 38 was prepared as follows:

One molecular equivalent of quinitol (1,4-cyclohexanediol) and four molecular equivalents of 2'ethylhexoic acid were heated together at 205235 C. in the presence of zinc dust, while an azeotropic mixture of water and 2- ethylhexoic acid was distilled off. The desired product was then removed under reduced pressure. The portion boiling at 166189 C./0.3 mm. was collected as a water-white liquid.

The above examples are merely illustrative of the manner whereby the various anti-kinking agents of our invention can be prepared. Many of these agents can be employed with marked effect not only in films intended for X-ray use, but in any coated film where a tendency toward desensitization as a result of kinking is exhibited. Many of the anti-kinking agents of our invention have never been recognized as having photographically useful properties.

What we claim as our invention and desire secured by Letters Patent of the United States is:

l. A light-sensitive photographic element comprising a support and a photographic silver halide emulsion on each side of the support, said emulsions containing an anti-kinking agent selected from the group consisting of alkylbenzothiazolium salts wherein the alkyl group contains at least 9 carbon atoms, 3-n-laurlyrhodanine, alkylene bis-(3,3 -rhodanines), 2-(A -imidazolinyl)disulfide, urazole, bis-(4 morpholinylthiocarbonyl)disulfide, alkyl S-(benzoyl)xanthates, amides of carboxylic acids containing at least 9 carbon atoms in the acid radical, and quinitol Z-ethylhexoate.

2. A light-sensitive photographic element suitable for use in X-ray photography comprising a support and a photographic gelatino silver halide emulsion on each side of the support, each of said emulsions containing the same anti-kinking agent selected from those represented by the following general formula:

wherein R8 represents an aryl group and R9 represents an alkyl group.

3. A light-sensitive photographic element suitable for use in X-ray photography comprising a support and a photographic gelatino silver halide emulsion on each side of the support, each of said emulsions containing 3-nlaurylrho'danine.

4. A light-sensitive photographic element suitable for use in X-ray photography comprising a support and a photographic gelatino silver halide emulsion on each side of the support, each of said emulsions containing ethyl S- (p-chlorobenzoyl) xanthate.

(References on following page) References Cited in the file of this patent UNITED STATES PATENTS Sheppard July 31, 1928 Brooker et a1. June 12, 1934 Middleton et a1 Feb. 15, 1944 

1. A LIGHT-SENSITIVE PHOTOGRAPHIC ELEMENT COMPRISING A SUPPORT AND A PHOTOGRAPHIC SILVER HALIDE EMULSION ON EACH SIDE OF THE SUPPORT, SAID EMULSIONS CONTAINING AN ANTI-KINKING AGENT SELECTED FROM THE GROUP CONSISTING OF ALKYLBENZOTHIAZOLIUM SALTS WHEREIN THE ALKYL GROUP CONTAINS AT LEAST 9 CARBON ATOMS, 3-N-LAURLYRHODANINE, ALKYLENE BIS-(3,3''-RHODANINES), 2-($2-IMIDAZOLINYL) DISULFIDE, URAZOLE, BIS-(4 - MORPHOLINYLTHIOCARBONYL) DISULFIDE, ALKYL S-(BENZOYL) XANTHATES, AMIDES OF CARBOXYLIC ACIDS CONTAINING AT LEAST 9 CARBON ATOMS IN THE ACID RADICAL, AND QUINITOL 2-ETHYLHEXOATE. 